Neurons build the nervous system, the system which includes the brain and spinal cord. On damage or death of these neurons, body is in no capacity to replace them and thus such conditions lead to neurodegenerative diseases which include Parkinson's, Alzheimer's and Huntington's disease.
Alzheimer's disease (AD) is a progressive neurodegenerative disease, characterized by memory loss, cognitive impairment, and functional decline. During early stages of the disease, sleep disturbances and forgetfulness are generally first presenting symptoms. In severe stages, patients with Alzheimer's disease (AD) require permanent observation, either by a home care professional or a family member.
Dementias are responsible for the greatest burden of disease with Alzheimer's. The cluster of symptoms seen in Alzheimer's disease (AD) is called dementia. Alzheimer's disease (AD) comprises approximately 60-80% of the total population suffering from dementia. The risk of developing Alzheimer's disease (AD) is believed to be determined by a combination of genetic, metabolic, behavioral, and environmental factors.
A progressive dementia associated with Alzheimer's disease is characterized by pronounced neurodegeneration in the entorhinal cortex, hippocampal CA1 and subiculum. The neurodegeneration present in hippocampus, cortex, and entorhinal cortex in Alzheimer's disease (AD) are the products of several neurodegenerative processes that occur at different stages of disease. Cholinergic abnormalities are the most problematic neurotransmitter deficiencies in Alzheimer's disease (AD). Acetylcholine (Ach) acts on muscarinic and nicotinic receptors in both peripheral and central nervous systems. Increased activation of nicotinic receptors in hippocampus and cortex elicits a therapeutic response, improving cognition and memory. Many current Alzheimer's disease (AD) therapies focus on the inhibition of Acetylcholine esterase (AChE), the enzyme that hydrolyzes Acetylcholine (Ach). These therapies may provide symptomatic relief in Alzheimer's disease (AD).
Alzheimer's disease is the leading cause of dementia worldwide. An estimated 5.2 million Americans of all ages have Alzheimer's disease in 2014. This includes an estimated 5 million people age 65 and older and approximately 200,000 individuals under age 65 who have younger-onset Alzheimer's. In US, one in nine people age 65 and older (11 percent) has Alzheimer's disease, about one-third of people age 85 and older (32 percent) have Alzheimer's disease. Of those with Alzheimer's disease, the vast majority (82 percent) are age 75 or older.
Acetylcholineesterase inhibitors (more often called as Cholinesterase inhibitors) and NMDA receptor antagonists are the two type of medications used in Alzheimer's treatment. The most common treatment for Alzheimer's disease (AD) is Cholinesterase inhibitors such as donepezil, rivastigmine, and galantamine. Cholinesterase inhibitors curb the breakdown of acetylcholine, the neurotransmitter in the brain, which is responsible for memory and learning. Cholinesterase inhibitors increase the levels of acetylcholine in the brain and may slow down the progression of symptoms. Memantine is a NMDA receptor antagonist which is generally recommended for the treatment of moderate to severe Alzheimer's disease.
The currently available therapies for Alzheimer's disease (AD) provide only symptomatic relief, and may not cure or prevent the disease from worsening over time. Secondly, a particular drug may not be beneficial to a patient considering the side effects suffered by a particular individual considering the stage of the disease. Since Alzheimer's disease (AD) is multifarious, with various etiologies, it seems unlikely that any one treatment or approach may be able to cure it. The modern approaches for treatment and research are focusing on several different aspects, like, maintaining mental function, managing behavioral symptoms, slowing or delaying the symptoms of the disease, preserving cognitive and functional processes, improving the patient's quality of life, delaying institutionalization, decreasing the caregiver burden.
Though the thought process in the same context is ongoing one may still look into approaches which can give promising results in this direction. Approaches considering the activity and mechanisms of the existing array of drugs or actives in order to treat Alzheimer's disease may be a techno-economical path forward in the desired direction.